48 results about "Digital elevation map" patented technology

A method and apparatus for performing wide area terrain mapping. The system comprises a digital elevation map (DEM) and mosaic generation engine that processes images that are simultaneously captured by an electro-optical camera (RGB camera) and a LIDAR sensor. The image data collected by both the camera and the LIDAR sensor are processed to create a geometrically accurate three-dimensional view of objects viewed from an aerial platform.

The invention discloses a 3D terrain imaging system of the interferometric synthetic aperture radar (InSAR) and an elevation mapping method thereof, which mainly solve the problems that the existing InSAR has bad imaging pragmaticality and can not implement 3D elevation mapping on the fast-changing terrain and the transilient terrain. The system comprises three sub-aperture antennas, a radar transmitter, a radar receiver and an imaging data processor; the imaging signal processor comprises a SAR image processing unit and an InSAR image processing unit. The invention receives radar echo through the three sub-apertures, then conducts SAR imaging process on the radar echo respectively received by the three sub-apertures, and then conducts InSAR imaging process on the obtained SAR complex pattern, wherein the InSAR imaging process comprises image registration, phase filtering and phase unfolding based on cluster analysis. The processed InSAR phase unfolded image is processed with an elevation inversion to recover a three dimensional digital elevation map. The invention has the advantages of wide adaptability to mapped terrains, and high imaging effectiveness, therefore, the invention can be used in the mapping of the 3D terrain.

An airborne reconnaissance system comprising: (1) Gimbals having at least two degrees of freedom; (2) At least one array of light sensors positioned on the gimbals, for being directed by the same within at least two degrees of freedom; (3) Map storage means for storing at least one Digital Elevation Map of an area of interest, divided into portions; (4) Inertial Navigation System for real-time providing to a gimbals control unit navigation and orientation data of the aircraft with respect to a predefined global axes system;(5) Portion selection unit for selecting, one at a time, another area portion from the area of interest; and (6) servo means for directing the gimbals. The system uses data from the inertial navigation system and from the digital elevation map for real-time calculating direction to selected area portions, and for maintaining the direction during integration of light from the terrain, and for producing corresponding images of area portions.

Methods and apparatus for detecting obstacles in the flight path of an air vehicle are described. The air vehicle utilizes a radar altimeter incorporating a forward looking antenna and an electronic digital elevation map to provide precision terrain aided navigation. The method comprises determining a position of the air vehicle on the digital elevation map, selecting an area of the digital elevation map in the flight path of the air vehicle, based at least in part on the determined air vehicle position, and scanning the terrain representing the selected map area with the forward looking antenna. The method also comprises combining the digital elevation map data for the selected map area with radar return data for the scanned, selected area and displaying the combined data to provide a representation of the terrain and obstacles in the forward flight path of the air vehicle.

A airborne reconnaissance system comprising: (1) Gimbals having at least two degrees of freedom; (2) At least one array of light sensors positioned on the gimbals, for being directed by the same within at least two degrees of freedom; (3) Map storage means for storing at least one Digital Elevation Map of an area of interest, divided into portions; (4) Inertial Navigation System for real-time providing to a gimbals control unit navigation and orientation data of the aircraft with respect to a predefined global axes system; (5) Portion selection unit for selecting, one at a time, another area portion from the area of interest; and (6) servo means for directing the gimbals. The system uses data from the inertial navigational system and from the digital elevation map for real-time calculating direction to selected area portions, and for maintaining the direction during integration of light from the terrain, and for producing corresponding images of area portions.

A method for enhancing a three dimensional image from frames of flash LIDAR data includes generating a first distance R_i from a first detector i to a first point on a surface S_i. After defining a map with a mesh Θ having cells k, a first array S(k), a second array M(k), and a third array D(k) are initialized. The first array corresponds to the surface, the second array corresponds to the elevation map, and the third array D(k) receives an output for the DEM. The surface is projected onto the mesh Θ, so that a second distance R_k from a second point on the mesh Θ to the detector can be found. From this, a height may be calculated, which permits the generation of a digital elevation map. Also, using sequential frames of flash LIDAR data, vehicle control is possible using an offset between successive frames.

A navigation system is described which includes a navigation processor, an inertial navigation unit configured to provide a position solution to the navigation processor, and a digital elevation map. The described navigation system also includes a radar altimeter having a terrain correlation processor configured to receive map data from the digital elevation map and provide a position solution based on radar return data to the navigation processor. A map quality processor within the navigation system is configured to receive map data from the digital elevation map and provide a map quality factor to the navigation processor which weights the position solution from the terrain correlation processor according to the map quality factor and determines a position solution from the weighted terrain correlation processor position solution and the position solution from the inertial navigation unit.

The invention belongs to the technical field of geographic information systems and remote sensing, specifically a three-dimensional ground object automatic extraction and scene reconstruction method based on geographic information and remote sensing data. The method mainly comprises a step of ground surface coverage type detection: extracting water areas, buildings, roads and vegetation from map data and optical image data; a step of building detection and height estimation: extracting the geographic information of a building and estimating the height of the building from an optical image; a step of vegetation detection and extraction: detecting the vegetation and carrying out the height estimation through a neural network; and a step of three-dimensional ground surface model building: building a three-dimensional ground surface through a digital elevation map and carrying out the embedding of ground objects. A three-dimensional scene which is automatically reconstructed based on the global geographic information and remote sensing data is real and accurate, can be updated quickly, and can support the VR/AR application (location services and virtual guide), and also can be used as a background environment model for electromagnetic environment simulation.

A method of detecting man-made structures in a digital representation of a terrain, wherein said representation is a digital elevation map, and wherein said method comprises the following steps: computing isolines in said digital elevation map; filtering said isolines on the basis of a size criterion; computing extremum isolines from the isolines filtered during the preceding step; and determining said regions of interest. The invention is applicable to any process involving supervision of a geographical site (e.g. planning cellular telecommunications networks).

A correlation method of real part and imaginary part in interference phase map includes using isoline window in size of m x n to carry out correlation operation for real part and imaginary part data of two complex maps for deriving out correlation coefficient C1, utilizing the same manner to drive out C2 by carrying out correlation operation for real part of the first complex map data and for imaginary part of the second complex map data, deriving out arc tangent for obtaining interference phase map by utilizing ratio of C1 and C2; using two accurate complex maps to generate interference phase map being free from coherent speckle noise.

The invention discloses a spaceborne laser altimeter in-orbit moon elevation detection uncertainty evaluation method which comprises the following steps of: screening an area of which the terrain change is flat from a laser altimeter moon surface elevation detection full-moon area; eliminating a pseudo elevation and calculating the area elevation mean value and the standard deviation in the screened area; analyzing various uncertainty influence factors influencing the elevation detection and the distribution density; and carrying out laser altimeter in-orbit moon elevation detection uncertainty evaluation in combination with the various influence factors and by utilizing the ''Monte Carlo Method for Evaluation of Measurement Uncertainty''specification and giving the elevation results. The method has the advantage that the elevation detection uncertainty can be given to the spaceborne laser altimeter in-orbit moon surface terrain elevation detection according to the selected area to provide a basis for further analyzing the source of laser altimeter measurement error and provide a reference and a basis for making a high-precision moon digital elevation map.

The invention provides an irregular terrain radio wave propagation factor prediction method based on a three-dimensional parabolic equation for solving the problem that a two-dimensional parabolic equation cannot consider the influence of transverse terrain to radio wave propagation properties. The irregular terrain radio wave propagation factor prediction method comprises the following steps: establishing a three-dimensional irregular terrain geometric model by using a digital elevation map; deducing a wide angle parabolic equation expressed by a bit function by using a maxwell equation; figuring out an initial field of the wide angle parabolic equation by using a current distribution function of an excitation source; figuring out the wide angle parabolic equation by using an improved step-by-step Fourier transform method to obtain a total field of the wide angle parabolic equation; constructing an attenuation function in a whole space, and correcting the amplitude of the total fieldof the wide angle parabolic equation; and calculating an irregular terrain radio wave propagation factor by using the total field of the wide angle parabolic equation considering the absorption boundary. By adoption of the irregular terrain radio wave propagation factor prediction method, the precision of prediction of the three-dimensional parabolic equation is improved, the application range ofthe digital elevation map is expanded, and the irregular terrain radio wave propagation factor prediction method can be applied to wireless communication and GPS positioning in complex environments.

A method of estimating land surface temperature lapse rate using an infrared image is disclosed. In the method of estimating land surface temperature lapse rate using an infrared image, a target area for the estimation of land surface temperature lapse rate is selected. The atmospheric transmittance of the target area is calculated. Reference temperature is estimated at a reference location set in the target area as desired. A temperature difference is calculated from the atmospheric transmittance and the estimated reference temperature, and then a temperature difference image is generated. Land surface temperature lapse rate is estimated from the temperature difference image and a Digital Elevation Map (DEM) in an identical area using an elevation-based temperature difference distribution.

The invention provides a distance information obtaining method for temperature correction of a thermal infrared imager. The distance information obtaining method comprises the following steps of: S1. installing the thermal infrared imager on a rotary platform, wherein the rotary platform is capable of rotating in the orientation direction and the pitching direction; S2. processing a digital elevation model by using a geometrical relationship according to position information of the thermal infrared imager in the space to obtain distances between the thermal infrared imager and an object on the earth surface along the direction of optical axis under various orientation angles and pitching angles. According to the distance information obtaining method, the distances between the thermal infrared imager and the object on the earth object along the direction of optical axis under various orientation angles and pitching angles can be calculated by using a method for calculating the distance between the object and the earth surface according to the position information of the thermal infrared imager in space and the digital elevation model of a working region of the thermal infrared imager.

The present invention discloses a coarse digital elevation map-based InSAR (interferometric synthetic aperture radar) absolute phase fuzzy estimation method. The main objective of the invention is to solve the problem of requiring ground accurate control points and the problem of complicated calibration computation in real-time digital elevation map generation of an existing radar. The method includes the following steps that: 1) the reference average height of a target scene is determined according to the coarse digital elevation map of the target scene; 2) a scene center slope distance is estimated according to the reference average height of the target scene; 3) the unwrapping phase and absolute phase of the scene center reference point are calculated; 4) the absolute phase fuzzy number of the whole scene is calculated according to the unwrapping phase and absolute phase of the scene center reference point; and 5) a real-time digital elevation map is obtained through inversion according to the absolute phase fuzzy number of the scene. With the coarse digital elevation map-based InSAR absolute phase fuzzy estimation method of the invention adopted, the absolute phase fuzzy number of a ground scene according to which no ground accurate control points exist and height changes sharply, can be estimated correctly and quickly. The method can be applied to the real-time signal processing system of an airborne radar.

A GNSS receiver includes a RF front end for receiving GNSS ranging signals, a navigation processor for calculating location from the ranging signals, and a repository of static data. The navigation processor includes the static data in the location calculation. Examples of static data include a digital elevation map, coordinates of tunnel entrances for use when the receiver resumes reception of the signals upon exiting a tunnel, and descriptions of structures in sufficient detail to enable multipath mitigation.

The invention discloses a comprehensive global path planning method based on a lunar surface digital elevation map, and belongs to the technical field of lunar exploration path planning. The method aims at solving the problems that the distance cost, the terrain cost and the sun illumination condition cost cannot be comprehensively considered in lunar surface path planning, and the searching timefor large-range path planning is too long. According to the method, lunar surface topographic features are extracted on the basis of a lunar surface DEM map, then a comprehensive smoothness map is generated on the basis of the lunar surface features, an effective solar energy distribution map is generated on the basis of lunar surface sun illumination information, and a multi-cost heuristic function is designed according to topographic comprehensive smoothness information and the effective solar energy distribution information; and multi-cost function values are taken as g (n) values of nodesin the A * algorithm, the nodes with the smaller g (n) values are selected for searching until a target node is searched, and backtracking is performed according to a parent table to construct a path.The method is used for moon detection path planning.

The invention discloses a method for suppressing a false sea surface target based on a digital elevation map and belongs to the field of airborne radars. The method comprises the following steps of 1, carrying out fragmentation treatment on a digital elevation map and storing the map; 2, according to the position of a current aircraft, the radar range and the processed storage data of the digital elevation map, loading terrain data in a local area and forming a corresponding suppressed terrain area; 3, according to the attitude and the target parameter of the aircraft, calculating the longitude and the latitude of a target; 4, acquiring the sea-land state of a position wherein the target is located; 5, performing suppression judgment according to the obtained altitude of the target and the height of the sea level. According to the method for suppressing the false sea surface target based on the digital elevation map, the limitation problem of suppressing a land false target based on a plane digital map can be solved, so that the influence of the radar on the false target during the sea detection process is effectively reduced. The detection efficiency is improved.

An interferometric radar comprising an arm (2), which rotates with respect to an axis (z) of a plane (zx) orthogonal to an axis of rotation (y), a system of linear-polarization antennas (1), which is fixed to said arm (2) for describing complete revolutions along a circular path (c) about said axis (y) and is oriented in a direction of sight (a) parallel to the axis (y), motor-drive means (3) for driving the arm (2), a data-acquisition and processing unit (10) operatively connected to said antenna (1) for acquiring a succession of images detected by the antenna during its revolution about the axis (y) and making differential interferometric calculations for measuring at least one component of the displacement of one or more targets in the field of view, or else for measuring the digital elevation map (DEM) of the scenario in the field of view.

A display provides optimized situational awareness to firefighting command personnel within a wildfire theatre. Lidar scanning data provides a digital elevation map of the wildfire theatre for the display. Geographic features such as lakes, roads, power lines and structures can be overlaid on the display. Lidar data utilizing multiple reflection signatures can be interpreted to represent fuel density and/or canopy height and such information can also be included upon the display. A burn area and active fire edge can be sensed by infrared scanner data and overlaid upon the display. The display can be utilized for input of firefighting command instructions, such as in the form of vectors or other annotations placed upon the display and correlated with airborne firefighting resources to be dropped at designated locations. Data provided to the display can be periodically updated to reflect the current situation. Firefighting resources are thus most effectively assigned.

The invention discloses a complex terrain electromagnetic scattering rapid simulation method based on a digital elevation map and a GPU. The method comprises the following steps: taking a DEM as actual terrain geometric model information input, carrying out preprocessing on terrain data according to the DEM, and obtaining a triangular surface element model; performing parallel calculation of a GPU end, including initial ray division, ray tracing and far-zone scattered field calculation; and transmitting a calculation result to the CPU end, calculating a radar scattering cross section, and carrying out post-processing on data to obtain an electromagnetic scattering simulation model. DEM (Digital Elevation Model) data is used as input of the actual terrain geometric model, a complex terrain shielding effect and a multi-scattering problem are further considered, a bounce ray (SBR) algorithm is combined with a GPU (Graphics Processing Unit) parallel acceleration technology, the electromagnetic scattering rapid simulation model suitable for the actual complex terrain is established, and rapid estimation of scattering echoes of each region of the complex terrain is realized.

The invention discloses a method for calculating a mean free path (MFP) of an exploration rover against complex terrain environment, which comprises selecting a locating point and a running direction of the exploration rover; judging passibility of a projection region of the exploration rover body; and calculating the MFP. The invention really reflects the exploration environment of the exploration rover by establishing a digital elevation map (DEM) of star terrain, and can be applied to complex terrain environment having various obstacles (such as slopes and irregular obstacles), and the calculation accuracy is not affected by the complex degree of terrain. The invention calculates the MFP by rotating the DEM of the star terrain at a fixed angle interval and straightly moving along the fixed direction on each map, simplifies the algorithm complicacy, and simultaneously improves the simulation rate. The method adopts the slope and elevation difference as a termination judgment condition of a single MFP calculation, and comprehensively considers climbing capacity and obstacle clearance capacity of the exploration rover.

The invention relates to the technical field of data processing, in particular to a method and device for determining the position of a risky electric tower, electronic equipment and a storage medium, and is used for improving the efficiency of determining the position of the risky electric tower. The main technical scheme comprises the following steps: acquiring an electric tower position marking graph corresponding to a digital elevation map; fusing the digital elevation map and the multiband orthoimage or RGB image corresponding to the digital elevation map into a three-channel information image; performing model training according to the three-channel information image and the filtered electric tower position marking graph to obtain an electric tower position identification model; inputting the target image into an electric tower position identification model to obtain an electric tower position identification result; for each electric tower in the electric tower position identification result, determining whether two other electric towers exist in a preset radius of the electric tower; and if two other electric towers do not exist in the preset radius, determining the electric tower within the preset radius range as the location area of the risk electric tower.